Please help ! I keep getting this error with my script.

I keep getting this error code and game wont play -the error code is-

"Assets/darts/CannonScript.cs(17,25): error CS0246: The type or namespace name `List' could not be found. Are you missing a using directive or an assembly reference?" the code look good so whats going on? please help

using UnityEngine; using System.Collections; using System.Collections.Generic;

     public class CannonScript : MonoBehaviour
     {
         // TrajectoryPoint and Ball will be instantiated
         public GameObject TrajectoryPointPrefeb;
         public GameObject BallPrefb;
 
         private GameObject ball;
         private bool isPressed, isBallThrown;
         private float power = 25;
         private int numOfTrajectoryPoints = 30;
         private List trajectoryPoints;
         //---------------------------------------    
         void Start ()
         {
             trajectoryPoints = new List();
             isPressed = isBallThrown =false;
             //   TrajectoryPoints are instatiated
             for(int i=0;i<numOfTrajectoryPoints;i++)
             {
                 GameObject dot= (GameObject) Instantiate(TrajectoryPointPrefeb);
                 dot.renderer.enabled = false;
                 trajectoryPoints.Insert(i,dot);
             }
         }
         //---------------------------------------    
         void Update ()
         {
             if(isBallThrown)
                 return;
             if(Input.GetMouseButtonDown(0))
             {
                 isPressed = true;
                 if(!ball)
                     createBall();
             }
             else if(Input.GetMouseButtonUp(0))
             {
                 isPressed = false;
                 if(!isBallThrown)
                 {
                     throwBall();
                 }
             }
             // when mouse button is pressed, cannon is rotated as per mouse movement and projectile trajectory path is displayed.
             if(isPressed)
             {
                 Vector3 vel = GetForceFrom(ball.transform.position,Camera.main.ScreenToWorldPoint(Input.mousePosition));
                 float angle = Mathf.Atan2(vel.y,vel.x)* Mathf.Rad2Deg;
                 transform.eulerAngles = new Vector3(0,0,angle);
                 setTrajectoryPoints(transform.position, vel/ball.rigidbody.mass);
             }
         }
         //---------------------------------------    
         // Following method creates new ball
         //---------------------------------------    
         private void createBall()
         {
             ball = (GameObject) Instantiate(BallPrefb);
             Vector3 pos = transform.position;
             pos.z=1;
             ball.transform.position = pos;
             ball.SetActive(false);
         }
         //---------------------------------------    
         // Following method gives force to the ball
         //---------------------------------------    
         private void throwBall()
         {
             ball.SetActive(true);    
             ball.rigidbody.useGravity = true;
             ball.rigidbody.AddForce(GetForceFrom(ball.transform.position,Camera.main.ScreenToWorldPoint(Input.mousePosition)),ForceMode.Impulse);
             isBallThrown = true;
         }
         //---------------------------------------    
         // Following method returns force by calculating distance between given two points
         //---------------------------------------    
         private Vector2 GetForceFrom(Vector3 fromPos, Vector3 toPos)
         {
             return (new Vector2(toPos.x, toPos.y) - new Vector2(fromPos.x, fromPos.y))*power;
         }
         //---------------------------------------    
         // Following method displays projectile trajectory path. It takes two arguments, start position of object(ball) and initial velocity of object(ball).
         //---------------------------------------    
         void setTrajectoryPoints(Vector3 pStartPosition , Vector3 pVelocity )
         {
             float velocity = Mathf.Sqrt((pVelocity.x * pVelocity.x) + (pVelocity.y * pVelocity.y));
             float angle = Mathf.Rad2Deg*(Mathf.Atan2(pVelocity.y , pVelocity.x));
             float fTime = 0;
 
             fTime += 0.1f;
             for (int i = 0 ; i < numOfTrajectoryPoints ; i++)
             {
                 float dx = velocity * fTime * Mathf.Cos(angle * Mathf.Deg2Rad);
                 float dy = velocity * fTime * Mathf.Sin(angle * Mathf.Deg2Rad) - (Physics2D.gravity.magnitude * fTime * fTime / 2.0f);
                 Vector3 pos = new Vector3(pStartPosition.x + dx , pStartPosition.y + dy ,2);
                 trajectoryPoints[i].transform.position = pos;
                 trajectoryPoints[i].renderer.enabled = true;
                 trajectoryPoints[i].transform.eulerAngles = new Vector3(0,0,Mathf.Atan2(pVelocity.y - (Physics.gravity.magnitude)*fTime,pVelocity.x)*Mathf.Rad2Deg);
                 fTime += 0.1f;
             }
         }
     }